I live in Maine were we have plenty of water, so I do not conserve water at all, and I find the chart to be rather high.
For instance, I have a 40 gallon electric hot water tank, yet use no cold when I shower, and it never runs out of water. So to say it takes 50 gallons sounds really high to me, I doubt I even use 20 gallons.
A 40 gallon bath seems high too. I have filled my 120 gallon stock tank by five gallon bucket, and I am not even sure I could get (8) 5 gallon buckets of water into my bath tub. Yes, it could be said that running the water first to get it warm would add to the gallons per tub estimate, but 40 gallons???
So it seems pretty high. If pressed, I would say for a more accurate result for my house, I would divide the listed amounts by 1/3 and probably be pretty close.
Yeah, this chart seems to err on the high side, leaning towards some wild guesses!
At least on the bathing numbers. If 40 gallons is a bath, and 50 (or 25) gallons for a shower, what?! If I stop the drain while I shower, no way it fills up as full as if I draw a bath...
If it were me, I'd take actual readings using a water meter over a known period and extrapolate (longer sample the better) or divert all the gray water to a tank and measure (messy, might miss some uses).
What your actual use is, will be far more useful than estimates. Although, over-building might only be costly money-wise, whereas under-building might be costly in many more ways...
A side benefit of water meters, is that they are sensitive instruments, with a tiny pointer/triangle that will clearly show tiny flows like a leaky faucet, or a pinhole leak in a pipe.
I was thinking the same thing- the amounts are absurdly high for me..... but for my siblings they would probably be spot on. (I never stopped taking navy showers, they were born a decade after the water shortage I grew up in and never learned to conserve water.) Checking your own usage using sampling is probably a much better idea.
I got this tall by not having enough crisco in my diet as a kid. This ad looks like it had plenty of shortening:
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